Abstract classes and interfaces in Java serve ... manipulates instance variables within concrete methods. From an object-oriented programming perspective, the main difference between an interface ...

This is because Java is “statically-typed” as opposed ... depending on how they interact with their class (instance variables vs static variables). You won’t need to understand these ...

but every instance of a bank account has a different number. The account ID is constant on a per-account basis, but it's not the same for every account. That's how final variables work. What is a ...